JPH07293416A - Ignition signal detecting device for internal combustion engine - Google Patents

Abstract

PURPOSE:To provide an ignition signal detecting device for internal combustion engine, in which miniaturization and cost reduction are realized. CONSTITUTION:The ignition signal detecting device is provided with a pulse shaping circuit C for generating specified pulse signals from primary voltage of an ignition coil 3, a timer circuit D for generating fixed-time pulses using the pulse signal as a trigger, a pulse detecting circuit E for continuously outputting hold signals on specified levels after the pulse signal is at least once detected. Further, the ignition signal detecting device is provided with a logical circuit 29 for generating the logical product of the hold signal and the fixed time pulse as an ignition signal, and a power supply key switch 2 for supplying power-supply voltage VB of a battery 1 to the ignition coil, the pulse shaping circuit, the timer circuit, and the pulse detecting circuit. Thus, the pulse detecting circuit is made of a monolithic IC consisting of simplified circuits to prevent the generation of false ignition signals at the time when the power supply key switch is turned ON.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ignition signal detecting device for an internal combustion engine which prevents an erroneous output of an ignition signal when a power key switch is turned on when ignition is detected by a primary current or a primary voltage from an ignition coil. In particular, the present invention relates to an ignition signal detection device for an internal combustion engine that realizes downsizing and cost reduction.

[0002]

2. Description of the Related Art Conventionally, in an ignition device for an internal combustion engine, it is necessary to detect an ignition signal to grasp an operating state. However, when the power key switch is turned on, the ignition signal may be erroneously detected. Therefore, various circuits have been proposed to prevent this.

FIG. 6 is a circuit diagram showing a conventional ignition signal detecting apparatus for an internal combustion engine, which is disclosed in, for example, Japanese Patent Laid-Open No. 1-240774. In the figure, 1 is the power supply voltage VB
For supplying a battery, 2 is a power key switch connected to the anode side of the battery 1, 3 is an ignition coil whose one end is connected to the battery 1 via the power key switch 2, and 4 is a secondary side of the ignition coil 3. It is a connected spark plug.

Reference numeral 5 is a CPU including a microcomputer, and 6 is a CP.
It is a power transistor drive circuit driven under the control of U5. Reference numeral 7 denotes a power transistor driven by the power transistor drive circuit 6, which is composed of a first transistor 7a and a second transistor 7b connected in Darlington, and the base of the first transistor 7a is an output terminal of the power transistor drive circuit 6. Connected to the first
The emitter of the transistor 7a of the second transistor 7 is
b, and the collectors of the transistors 7a and 7b are connected to the other end of the ignition coil 3 on the primary side. An ignition device is configured by the battery 1 to the power transistor 7 described above.

Reference numeral 8 is a first resistor whose one end is connected to a connection point a between the collectors of the transistors 7a and 7b and the ignition coil 3, and 9 is between the other end of the first resistor 8 and the ground. The inserted second resistor, 10 is the first diode whose anode is connected to the connection point of the resistors 8 and 9,
Reference numeral 11 is a first capacitor inserted between the cathode of the first diode 10 and the ground, 12 is a zener diode connected in parallel between both ends of the first capacitor 11 and the anode is grounded, and 13 is a first Is a third resistor whose one end is connected to the cathode of the diode, and 14 is a fourth resistor inserted between the other end of the third resistor 13 and the ground.

Reference numeral 15 is a connection point b between the resistors 13 and 14.
Is a third transistor whose base is connected to, and whose emitter is grounded. Reference numeral 16 is a fifth resistor, one end of which is connected to the battery 1 via the power key switch 2, and the other end of which is connected to the collector of the third transistor 15. Reference numeral 17 is a second capacitor inserted between the other end of the fifth resistor 16 and the ground.

Reference numeral 18 is a comparator composed of an open collector gate logic, and its inverting input terminal (-) is a connection point between the collector of the third transistor 15 and the fifth resistor 16 and the second capacitor 17. The non-inverting input terminal (+) is connected to c and is connected to a reference power source that outputs the reference voltage VTH.

The output terminal of the comparator 18 is directly connected to the ground when the voltage Vc at the connection point c is higher than the reference voltage VTH, and the output terminal is opened when the voltage at the connection point c is equal to or lower than the reference voltage VTH. It has become. Also, the fifth
Resistor 16 and second capacitor 17 and comparator 18 of
A constant time timer circuit is configured by the above.

Reference numeral 19 is a sixth resistor whose one end is connected to the output terminal of the comparator 18, 20 is an output circuit connected to the other end of the sixth resistor 19, and 21 is each of the resistors 13 and 14. It is an inverter connected to the connection point b. Reference numeral 22 is a fourth transistor whose base is connected to the output terminal of the inverter 21 and whose emitter is grounded. Reference numeral 23 is a seventh resistor whose one end is connected to the battery 1 via the power key switch 2 and whose other end is connected to the collector of the fourth transistor 22.

Reference numeral 24 is a second diode whose anode is connected to the connection point between the seventh resistor 23 and the collector of the fourth transistor 22, and whose cathode is the sixth resistor 19
And the output circuit 20 are connected to the connection point d. Reference numeral 25 is a third capacitor inserted between the cathode of the second diode 24 and the ground.

The inverter 21 to the third capacitor 25 constitute erroneous pulse prevention means for the ignition signal when the power key switch 2 is turned on. In addition, the seventh resistor 23, the second diode 24, and the third capacitor 25 form a power supply circuit for the output terminal of the comparator 18. Further, the above first resistor 8 to
The third capacitor 25 constitutes an ignition signal detection circuit.

Further, the third resistor 13 to the third transistor 15 and the comparator 18 to the second diode 24 are
Configured as a monolithic IC. Note that the capacitor capacity that can be configured as a monolithic IC is usually 30
Whereas up to PF, the third capacitor 25
Has a large capacity of about 1000 PF, for example. Therefore, the third capacitor 25 is an external component together with the fifth resistor 16 and the second capacitor 17, the Zener diode 12, the first capacitor 11, and the like.

Next, the operation of the conventional ignition signal detecting apparatus for an internal combustion engine shown in FIG. 6 will be described with reference to the timing chart of FIG. In FIG. 7, (A)-
(E) is the power supply voltage VB and the connection points a to d in FIG.
The respective voltage waveforms of are shown. First, when the power key switch 2 is turned on, the power supply voltage VB from the battery 1 is supplied to the primary side of the ignition coil 3, as shown in FIG.

However, when the power key switch 2 is turned on, the primary winding of the ignition coil 3 is not driven yet, so the input voltage of the inverter 21 (voltage at the connection point b) is at L level, and 21 output voltage is H
Since the level becomes the level, the fourth transistor 22 is turned on.

Therefore, the current supplied from the battery 1 flows through the seventh resistor 23 and the fourth transistor 22 to the ground, does not flow into the third capacitor 25, and charges the third capacitor 25. The voltage is 0V
Is.

Further, the voltage at the connection point b is L level,
Since the third transistor 15 is turned off, the second capacitor 17 starts to be charged with electric charge from the battery 1 via the fifth resistor 16. At this time, the voltage at the one end of the second capacitor 17, that is, the connection point c is equal to or lower than the reference voltage VTH, so that the output terminal of the comparator 18 is open.

As described above, since the terminal voltage of the third capacitor 25 is 0V and the output terminal of the comparator 18 is open at the time when the power key switch 2 is turned on, the output terminal of the output circuit 20 is connected to the input terminal side. The voltage at the connection point d is 0V
Becomes Therefore, an erroneous pulse when the power key switch 2 is turned on (see the broken line in FIG. 7E) does not occur at the connection point d, and erroneous ignition detection can be prevented.

Subsequently, when the ignition control signal is generated from the CPU 5 while the power key switch 2 is turned on, the power transistor drive circuit 6 is driven, so that the power transistor 7 is turned on and off. This allows
The primary winding in the ignition coil 3 is turned on and off, and
As shown in (B), a primary output voltage is generated at the connection point a. In particular, when the primary winding is cut off corresponding to the ignition timing, a high voltage surge voltage is generated at the connection point a.

Due to this surge voltage, a high voltage is generated from the secondary side of the ignition coil 3, and the secondary high voltage causes sparks to be generated in the spark plug 4 to perform ignition control. On the other hand, the surge voltage generated at the connection point a is rectified via the first diode 10 and converted into a constant voltage via the Zener diode 12, and the waveform is shaped as shown in FIG. And applied to the third transistor 15.

The inverter 21 sets the output voltage to the H level in response to the pulse voltage at the connection point b (see FIG. 7C) to turn off the fourth transistor 22 for a moment, and during this off period. , The third capacitor 25 is rapidly charged from the battery 1 via the seventh resistor 23 and the second diode 24.

Similarly, the third transistor 15 is momentarily turned on by the pulse voltage at the connection point b to discharge the second capacitor 17. Therefore, as shown in FIG. 7D, the voltage at the one end of the second capacitor 17, that is, the connection point c becomes equal to or lower than the reference voltage VTH, so that the output terminal of the comparator 18 is opened. ), The charging voltage of the third capacitor 25 is generated at the connection point d.

Since the third transistor 15 is momentarily turned on by the pulse voltage at the connection point b, the pulse voltage is zero.
After the voltage becomes V and the third transistor 15 is turned off,
The second capacitor 17 is charged again, and the voltage at the connection point c gradually rises, as shown in FIG.

When the voltage at the connection point c exceeds the reference voltage VTH due to the charging of the second capacitor 17, the output terminal of the comparator 18 is directly connected to the ground, so that the charge charged in the third capacitor 25 is It is discharged through the sixth resistor 19. As a result, the voltage at the connection point d on the input side of the output circuit 20 becomes 0 V, and then the voltage at the connection point b remains unchanged until the primary winding of the ignition coil 3 is cut off and a surge voltage is generated at the connection point a. It remains 0V.

As described above, while the voltage at the connection point b is 0 V, the output voltage of the inverter 21 is at the H level and the fourth transistor 22 is turned on, so that the charging of the third capacitor 25 is blocked. It In addition, since the third transistor 15 remains off, the second capacitor 1
Due to the charging of 7, the voltage at the connection point c is higher than the reference voltage VTH, and the output terminal of the comparator 18 remains directly connected to the ground.

As a result, the voltage at the connection point d is fixed at 0 V until the primary winding of the ignition coil 3 is cut off again and a surge voltage is generated. Therefore, as shown in FIG. 7E, a constant time pulse having a constant width is obtained, and this constant time pulse is supplied to the output circuit 20 and used as an ignition signal.

[0026]

As described above, the conventional ignition signal detection device for an internal combustion engine prevents the generation of an erroneous pulse (broken line in FIG. 7E) of the ignition signal when the power key switch 2 is turned on. In order to achieve this, a power supply circuit including a large-capacity third capacitor 25 is used.
And the like must be provided as external parts of the monolithic IC, and the number of parts is increased, so that miniaturization and cost reduction cannot be realized.

The present invention has been made to solve the above problems, and an object of the present invention is to obtain an ignition signal detection device for an internal combustion engine which realizes downsizing and cost reduction by simplifying the circuit configuration. .

[0028]

An ignition signal detecting apparatus for an internal combustion engine according to claim 1 of the present invention detects ignition of an internal combustion engine based on a primary voltage generated in a power transistor for driving an ignition coil. A pulse shaping circuit for shaping a waveform of a primary voltage to generate a predetermined pulse signal in an ignition signal detection device for an internal combustion engine that generates an ignition signal,
A timer circuit that generates a constant time pulse by using a pulse signal as a trigger, a pulse detection circuit that continues to output a holding signal of a predetermined level after the pulse signal is detected at least once, and a logical product of the holding signal and the constant time pulse A logic circuit that generates an ignition signal and a power supply key switch that supplies the power supply voltage of the battery to the ignition coil, the pulse shaping circuit, the timer circuit, and the pulse detection circuit, and the pulse detection circuit is composed of a monolithic IC. is there.

An ignition signal detecting apparatus for an internal combustion engine according to a second aspect of the present invention detects an ignition of the internal combustion engine based on a primary current from an ignition coil and generates an ignition signal. In the device, a pulse shaping circuit that shapes the waveform of the primary current to generate a predetermined pulse signal, a timer circuit that generates a fixed-time pulse by using the pulse signal as a trigger, and a predetermined level after the pulse signal is detected at least once. Detection circuit that continues to output the hold signal of the battery, a logic circuit that generates a logical product of the hold signal and the constant time pulse as an ignition signal, an ignition coil for the power supply voltage of the battery, a pulse shaping circuit, a timer circuit and a pulse detection circuit And a power supply key switch for supplying power to the pulse detection circuit, and the pulse detection circuit is composed of a monolithic IC.

An internal combustion engine ignition signal detection device according to a third aspect of the present invention is the ignition signal detection device according to the first or second aspect, wherein the pulse detection circuit includes a NOR gate to which a pulse signal is applied to one input terminal, The feedback inverter is inserted between the output terminal of the NOR gate and the other input terminal, and the output inverter connected to the output terminal of the NOR gate.

According to a fourth aspect of the present invention, in the ignition signal detecting apparatus for the internal combustion engine according to the second aspect, the pulse shaping circuit includes a comparator for comparing the detected voltage of the primary current with the reference voltage, and the logic circuit. Is composed of an AND gate having three input terminals and outputs a voltage signal in response to the pulse signal to the third
Input signal.

[0032]

According to the first aspect of the present invention, the timer circuit generates the constant time pulse by using the pulse signal obtained by shaping the primary voltage of the ignition coil as a trigger, and after detecting the pulse signal,
A holding signal is generated from a pulse detection circuit formed of a monolithic IC, and a logical product of the holding signal and the constant time pulse is generated as an ignition signal. This prevents the timer circuit from outputting to the final stage even if the timer circuit erroneously generates a fixed-time pulse from the time when the power key switch is turned on until the pulse signal is generated.

Further, according to a second aspect of the present invention, the timer circuit generates a constant time pulse by using the pulse signal obtained by shaping the primary current of the ignition coil as a trigger, and after detecting the pulse signal, the pulse formed by the monolithic IC. A holding signal is generated from the detection circuit, and a logical product of the holding signal and the constant time pulse is generated as an ignition signal. This prevents the timer circuit from outputting to the final stage even if the timer circuit erroneously generates a fixed-time pulse from the time when the power key switch is turned on until the pulse signal is generated.

Further, in the third aspect of the present invention, the pulse detection circuit is composed of a NOR gate including a transistor capable of being formed into a monolithic IC, an inverter, and the like, and an external capacitor or the like is unnecessary.

Further, according to a fourth aspect of the present invention, the pulse shaping circuit is configured by a comparator which compares the detected voltage of the primary current with the reference voltage to generate a pulse signal, and the capacitor in the pulse shaping circuit is unnecessary. .

[0036]

【Example】

Example 1. (Corresponding to Claim 1 and Claim 2) Hereinafter, Embodiment 1 of the present invention will be described with reference to the drawings. 1 is a circuit diagram showing a first embodiment of the present invention, in which 1 to 20 and a to d are the same as those described above. A is ignition coil 3 to
Ignition device composed of power transistor 7, B is an ignition signal detection circuit composed of first resistor 8 to output circuit 20 and NOR gate 26 to be described later to constant voltage circuit 30, and C is first resistor 8 to. A pulse shaping circuit composed of the fourth resistor 14, and D is a timer circuit composed of the third transistor 15 to the sixth resistor 19.

Reference numeral 26 is a NOR gate having two input terminals, one of which is connected to the connection point b.
Reference numeral 27 is a feedback inverter inserted between the output terminal of the NOR gate 26 and the other input terminal, and 28 is the NOR gate 2
6 is an output inverter connected to the output terminal 6 of the pulse detection circuit E. When the H-level signal is input even once from the connection point b, the pulse detection circuit E latches the H-level holding signal and generates it from the output point e, and functions as a memory circuit.

29 is an AND gate having two input terminals, one input terminal is connected to the output terminal of the timer circuit D, that is, the connection point d, and the other input terminal is connected to the output point e of the pulse detection circuit E. Has been done. AND gate 2
The output point f of 9 is connected to the output circuit 20.

Reference numeral 30 is a constant voltage circuit inserted between the power key switch 2 and the ground. An output terminal for supplying a constant voltage is connected to one end of the fifth resistor 16 in the timer circuit D. There is. Although not shown, the constant voltage circuit 30
The constant voltage output of is also supplied to the pulse detection circuit E.

FIG. 2 is a circuit diagram showing a concrete configuration example of the pulse detection circuit E in FIG. In FIG. 2, reference numerals 261 and 262 denote grounded-emitter transistors forming the NOR gate 26, and 263 is a resistor forming the NOR gate 26. The transistor 261 has a base connected to the connection point b, a collector connected to the collector of the transistor 262, and a resistor 263 connected to the output terminal of the constant voltage circuit 30.

271 and 272 are feedback inverters 2
Transistors 273 forming 7 are resistors forming the feedback inverter 27. The transistor 271 is
The base is connected to the collectors of the transistors 261 and 262, the emitter is grounded, and the collector is connected to the base of the transistor 262 and the collector of the transistor 272. The transistor 272 has an emitter connected to the output terminal of the constant voltage circuit 30 via the resistor 273.

Reference numeral 281 is a transistor forming the output inverter 28, and 282 is a resistor forming the output inverter 28. The base of the transistor 281 is connected to the collectors of the transistors 261 and 262,
The emitter is grounded and the collector is connected to the constant voltage circuit 30 via the resistor 282.

Reference numerals 275 and 276 denote collector-grounded transistors forming a constant current circuit, which control the base current of the transistor 272 in the feedback inverter 27 to be constant. The base of the transistor 274 is the transistor 2
It is connected to the collector of 75 and the emitter is transistor 2
It is connected to the base of 75.

Reference numeral 276 is a resistor inserted between the emitter of the transistor 275 and the output terminal of the constant voltage circuit 30,
277 is a resistor inserted between the collector of the transistor 275 and the ground. As shown in FIG. 2, since the pulse detection circuit E is composed of a transistor circuit, it can be composed of a monolithic IC instead of an external component.

Next, the operation of the first embodiment of the present invention shown in FIG. 1 will be described with reference to the timing chart of FIG. In FIG. 3, (A) to (E) correspond to (A) to (E) in FIG. 7, respectively, and (F).
Shows the voltage waveform at the output point e of the pulse detection circuit E, and (G) shows the output point f of the AND gate 29, that is, the voltage waveform of the input terminal of the output circuit 20.

Now, when the power key switch 2 is turned on, the power supply voltage VB as shown in FIG. 3A is supplied to the ignition coil 3 and the constant voltage circuit 30, and the constant voltage generated from the constant voltage circuit 30. Is supplied to the second capacitor 17 via the fifth resistor 16 in the timer circuit C, and is also supplied to the pulse detection circuit E.

At this time, since the third transistor 15 in the timer circuit C is in the off state unless a surge voltage is generated on the primary side of the ignition coil 3 as described above, one end of the second capacitor 17, that is, the connection point c. The voltage of is integrated by the fifth resistor 16 and the second capacitor 17, and becomes as shown in FIG.

Then, similarly to the above, when a control signal is generated from the CPU 5, the power transistor drive circuit 6 controls the conduction and interruption of the power transistor 7,
A primary voltage as shown in FIG. 3B is generated at the connection point a on the primary side of the ignition coil 3. The primary voltage at the connection point a becomes a pulse signal at the connection point b as shown in FIG. 3C via the pulse shaping circuit C.

The third transistor 15 is turned on by the pulse signal at the connection point b, and during this on period, the third transistor 15 shown in FIG.
As in (C), the voltage at the connection point c is 0V. On the other hand, during the off period of the third transistor 15 after the pulse signal at the connection point b has been turned off, the voltage at the connection point c becomes equal to the voltage waveform integrated by the fifth resistor 16 and the second capacitor 17. Become.

The voltage at the connection point c is compared with the reference voltage VTH by the comparator 18, and the voltage at the connection point c is compared with the reference voltage VTH.
In the following cases, the output signal of the timer circuit C is shown in FIG.
Fixed time pulse (ignition signal) with a predetermined width as shown in (E)
Is generated from the connection point d and is applied to one input terminal of the AND gate 29.

Next, the operation of the pulse detection circuit E will be described. The pulse detection circuit E is reset when the constant voltage is supplied from the constant voltage circuit 30 when the input voltage from the connection point b is L level (0 V), and the voltage at the output point e is 0 V.
And

When the power key switch 2 is turned on, the output voltage of the pulse shaping circuit C, that is, the voltage at the connection point b is 0 V until the primary voltage of the ignition coil 3 is generated, as shown in FIG. 3 (C). Therefore, the voltage at the output point e of the pulse detection circuit E is also 0 V as shown in FIG.

In this way, the output point e of the pulse detection circuit E
3 is being applied to the AND gate 29, the voltage at the output point f of the AND gate 29 remains at the output point f of the AND gate 29 even if a constant time pulse is generated from the output point of the timer circuit C, that is, the connection point d. It remains at 0V as in (G). Therefore, the false ignition signal Pe generated when the power key switch 2 is turned on is not input to the output circuit 20.

Next, when the primary current of the ignition coil 3 is cut off by turning on / off the power transistor 7, a primary voltage is generated at the collector (connection point a) of the power transistor 7. Therefore, the pulse shaping circuit C generates a pulse signal at the connection point b as shown in FIG.

When any one of the pulse signals is input to the NOR gate 26 in the pulse detection circuit E, the voltage at the output point e of the pulse detection circuit E is fixed at the H level as shown in FIG. 3 (F). It Therefore, the H-level voltage is continuously applied to the AND gate 29 until the power key switch 2 is turned off.

As described above, the pulse detection circuit E generates a constant-time pulse (misfire signal) from the timer circuit D over the period from when the power key switch 2 is turned on to when the pulse signal is first input. Even if it is done, the ignition signal is prevented from being applied to the output circuit 20 at the final stage.

As a result, the fixed-time pulse from the timer circuit D is applied to the output circuit 20 as an ignition signal only when a predetermined primary voltage is generated at the connection point a, and an erroneous pulse is generated when the power key switch 2 is turned on. Can be prevented. In addition, a pulse detection circuit E serving as an erroneous pulse prevention circuit
Is composed of a small number of parts and is composed of a monolithic IC without an external capacitor or the like, so that downsizing and cost reduction can be realized.

Example 2. (Corresponding to claims 2 to 4)
Although the primary voltage of the ignition coil 3 is detected to obtain the ignition signal in the first embodiment, the primary current of the ignition coil 3 may be detected. In this case, since the primary current waveform has a sufficiently long width, the large-capacity first capacitor 11 for ensuring the pulse width of the pulse signal becomes unnecessary.

The primary voltage of the ignition coil 3 is 500V.
The detection voltage of the primary current is several 10
Since it is about mV, the withstand voltage of each component in the pulse shaping circuit can be set sufficiently low, and the overall size of the device and the cost can be further reduced.

FIG. 4 is a circuit configuration diagram showing a second embodiment of the present invention in which an ignition signal is obtained based on the primary current of the ignition coil 3, and is 1 to 7, 15 to 20, 26 to 28, and 3.
0, b to f and E are the same as described above. Also,
29i and Ai to Di are 29 and A to, respectively.
Corresponds to D.

In this case, the AND gate 29i has three input terminals, and the voltage of the connection point g (described later) in the timer circuit Di is applied to the third input terminal. Also,
The ignition device Ai includes a resistor R1 for detecting the primary current i flowing through the ignition coil 3, and the resistor R1 is inserted between the emitter of the power transistor 7 and the ground. ai is a connection point between the emitter of the power transistor 7 and the resistor R1.

Reference numeral 31 represents the voltage at the connection point ai as the reference voltage VTH.
It is a comparator for comparing with 1. The inverting input terminal (−) is connected to the connection point ai, and the non-inverting input terminal (+) is connected to the reference voltage power supply. The comparator 31 inverts the output voltage from the L level to the H level when the voltage at the connection point ai exceeds the reference voltage VTH1. 32 is a comparator 3
1 is a resistor connected to the output terminal.

Reference numeral 33 is a transistor whose on / off is controlled by the output voltage of the comparator 31, whose base is connected to the output terminal of the comparator 31 via the resistor 32 and whose emitter is grounded. Reference numeral 34 is a resistor inserted between the collector of the transistor 33 and the output terminal of the constant voltage circuit 30, and constitutes a pulse shaping circuit Ci together with the comparator 31 to the transistor 33. The voltage at the connection point b between the collector of the transistor 33 and the resistor 34 is
i and the pulse detection circuit E.

Reference numerals 35 and 36 denote a pair of transistors inserted in the input side of the timer circuit Di, each emitter is grounded, and the collector of the input side transistor 35 is connected to the base of the next stage transistor 36. The collector of the latter transistor 36 is the third transistor 1
5 is connected to the base. Reference numerals 37 and 38 denote resistors provided in the timer circuit Di, which are respectively inserted between the collector of each transistor and the output terminal of the constant voltage circuit 30.

A connection point g between the collector of the transistor 35 and the base of the transistor 36 generates a voltage signal (a signal obtained by inverting the pulse signal at the connection point b) in response to the pulse signal generated at the connection point b, This voltage signal is applied to the third input terminal of the AND gate 29i. Further, the comparator 18 compares the voltage at the connection point c with the reference voltage VTH2 and generates a constant time pulse at the connection point d.

FIG. 5 is a timing chart for explaining the operation of the second embodiment of the present invention. The waveforms of power supply voltage VB and primary current i in FIG. 4 and the voltage waveforms at points ai and b to g are shown. Indicates.

Next, the operation of the second embodiment of the present invention shown in FIG. 4 will be described with reference to FIG. In this case, the pulse width of the pulse signal generated from the pulse shaping circuit Ci at the connection point b is long, so that the timer circuit Di
From the connection point d, and the AND gate 29i ANDs the three voltages at the points d, e and g to output the final ignition signal. The operation is the same as that of the first embodiment except that it is generated.

First, when the power key switch 2 is turned on, the power supply voltage VB is supplied to the constant voltage circuit 30, and the constant voltage from the constant voltage circuit 30 is supplied to each of the circuits Ci, Di and E in the ignition signal detection circuit Bi. Is supplied to. When the ignition coil 3 is driven, the primary current i flows toward the ground through the resistor R1, and the voltage (see FIG. 5) represented by the product of the primary current i and the resistance value of the resistor R1 is generated. It occurs at the connection point ai.

The voltage at the connection point ai is the pulse shaping circuit Ci
Is input to the comparator 31 in the
(See), it has a long waveform. When the voltage at the connection point ai exceeds the reference voltage VTH1, the comparator 31 sets the output voltage to the L level to turn off the transistor 33, and as shown in FIG. 5, generates a pulse signal at the H level at the connection point b.

This pulse signal causes the timer circuit Di to operate, and the transistor 35 is turned on first,
The voltage at the connection point g becomes L level. At this time, the transistor 36 is turned off and the third transistor 15 is turned on, so that the voltage at the connection point c becomes L level. Therefore,
The output voltage of the comparator 18, that is, the voltage at the connection point d becomes H level.

Next, when the pulse signal from the connection point b is turned off, the voltage at the connection point g becomes H level because the transistor 35 is turned off. Also, the transistor 36 is turned on, and the third
By turning off the transistor 15 of
Voltage gradually rises as the second capacitor 17 is charged. Then, the voltage at the connection point c is the reference voltage V
When TH2 is exceeded, the output voltage of the comparator 18, that is, the voltage at the connection point d becomes L level.

On the other hand, the pulse detection circuit E generates the H level voltage from the output point e from the time when the H level pulse signal is generated from the connection point b in response to the driving of the ignition coil 3 as described above. Keeps on doing. Therefore, the AND gate 29i generates a pulse signal from the connection point b, and L
A voltage (ignition signal) which becomes H level is generated at the output point f until the constant time pulse from the connection point d falls to L level from the time of falling to the level. As a result, the same operational effects as described above can be obtained, and further downsizing and cost reduction can be realized.

Example 3. In the second embodiment, the transistors 35 to 38 are provided in the timer circuit Di,
Although the voltage signal obtained by inverting the pulse signal at the connection point b is obtained from the connection point g between the transistors 35 and 36, instead of the transistors 35 to 38, the connection point b is obtained.
It is also possible to directly provide an inverter (not shown) in and to apply the output signal of this inverter to the third input terminal of the AND gate 29i. As a result, the number of parts can be further reduced, and further downsizing and cost reduction can be realized.

[0074]

As described above, according to the first aspect of the present invention, the ignition of the internal combustion engine is detected based on the primary voltage generated in the power transistor for driving the ignition coil,
In an ignition signal detection device for an internal combustion engine that generates an ignition signal, a pulse shaping circuit that shapes a waveform of a primary voltage to generate a predetermined pulse signal, a timer circuit that generates a fixed time pulse by using the pulse signal as a trigger, and a pulse. A pulse detection circuit that continues to output a holding signal of a predetermined level after a signal is detected at least once, a logic circuit that generates a logical product of a holding signal and a fixed-time pulse as an ignition signal, and a power supply voltage of a battery to an ignition coil , A pulse shaping circuit, a timer circuit, and a power supply key switch to supply to the pulse detection circuit, and the pulse detection circuit is configured by a monolithic IC consisting of a simple circuit with no external parts. As a result, an ignition signal detection device for an internal combustion engine that is compact and cost-effective can be obtained. There is an effect.

Further, according to claim 2 of the present invention, in the ignition signal detecting device for an internal combustion engine, which detects ignition of the internal combustion engine based on the primary current from the ignition coil and generates an ignition signal, the waveform of the primary current A pulse shaping circuit that shapes the pulse signal to generate a predetermined pulse signal, a timer circuit that generates a constant time pulse by using the pulse signal as a trigger, and continues to output a holding signal of a predetermined level after the pulse signal is detected at least once. A pulse detection circuit, a logic circuit that generates a logical product of a hold signal and a constant-time pulse as an ignition signal, a power supply key switch that supplies a power supply voltage of a battery to an ignition coil, a pulse shaping circuit, a timer circuit, and a pulse detection circuit. The pulse detection circuit is composed of a monolithic IC consisting of a simple circuit with no external parts, and erroneous ignition when the power key switch is turned on. Since so as to prevent the occurrence of items, the effect of further miniaturization and ignition signal detection apparatus which realizes cost reduction is obtained.

According to a third aspect of the present invention, in the pulse detecting circuit according to the first or second aspect, a NOR gate to which a pulse signal is applied to one input terminal, an output terminal of the NOR gate, and the other of the NOR gate are provided. A monolithic IC composed of a feedback inverter inserted between the input terminal and an output inverter connected to the output terminal of the NOR gate.
Since it can be configured inside, there is an effect that an ignition signal detection device for an internal combustion engine that surely realizes downsizing and cost reduction can be obtained.

According to claim 4 of the present invention, in claim 2, the pulse shaping circuit includes a comparator for comparing the detected voltage of the primary current with a reference voltage, and the logic circuit has three input terminals. Since the voltage signal in response to the pulse signal is used as the third input signal, it is possible to obtain an ignition signal detection device for an internal combustion engine that realizes further downsizing and cost reduction. .

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing a specific configuration example of a pulse detection circuit in FIG.

FIG. 3 is a timing chart for explaining the operation of the first embodiment of the present invention.

FIG. 4 is a circuit configuration diagram showing a second embodiment of the present invention.

FIG. 5 is a timing chart for explaining the operation of the second embodiment of the present invention.

FIG. 6 is a circuit configuration diagram showing a conventional ignition signal detection device for an internal combustion engine.

FIG. 7 is a timing chart for explaining the operation of a conventional ignition signal detection device for an internal combustion engine.

[Explanation of symbols]

1 battery, 2 power key switch, 3 ignition coil, 7 power transistor, 26 NOR gate, 27
Feedback inverter, 28 output inverter, 29,
29i AND gate (logic circuit), 31 comparator, a
A connection point where primary voltage is generated, ai connection point where primary current detection voltage is generated, b connection point where pulse signal is generated, d connection point where constant time pulse is generated, e output point where hold signal is generated, f An output point that produces an ignition signal,
g A connection point that produces a voltage signal in response to a pulse signal,
C, Ci pulse shaping circuit, D, Di timer circuit, E
Pulse detection circuit, VB power supply voltage, VTH1 reference voltage.

Claims (4)

[Claims] 1. An ignition signal detection device for an internal combustion engine, which detects ignition of an internal combustion engine based on a primary voltage generated in a power transistor for driving an ignition coil and generates an ignition signal, wherein a waveform of the primary voltage is A pulse shaping circuit that shapes the pulse signal to generate a predetermined pulse signal, a timer circuit that generates a constant time pulse by using the pulse signal as a trigger, and outputs a holding signal of a predetermined level after the pulse signal is detected at least once. A pulse detection circuit that continues, a logic circuit that generates a logical product of the holding signal and the constant time pulse as the ignition signal, a power supply voltage of a battery, the ignition coil, the pulse shaping circuit, the timer circuit, and the pulse detection A pulse key switch for supplying power to the circuit, wherein the pulse detection circuit is composed of a monolithic IC. Ignition signal detector for internal combustion engine. 2. An ignition signal detection device for an internal combustion engine, which detects ignition of an internal combustion engine based on a primary current from an ignition coil and generates an ignition signal, wherein a waveform of the primary current is shaped to generate a predetermined pulse signal. A pulse shaping circuit that generates a pulse signal; a timer circuit that generates a fixed-time pulse by using the pulse signal as a trigger; a pulse detection circuit that continues to output a holding signal of a predetermined level after the pulse signal is detected at least once; A logic circuit that generates a logical product of a signal and the constant time pulse as an ignition signal; and a power supply key switch that supplies a power supply voltage of a battery to the ignition coil, the pulse shaping circuit, the timer circuit, and the pulse detection circuit. An ignition signal detection device for an internal combustion engine, wherein the pulse detection circuit is composed of a monolithic IC. 3. The pulse detection circuit includes a NOR gate to which the pulse signal is applied to one input terminal, a feedback inverter inserted between the output terminal of the NOR gate and the other input terminal, and the NOR gate. 3. An ignition signal detecting device for an internal combustion engine according to claim 1 or claim 2, wherein the ignition signal detecting device comprises an output inverter connected to the output terminal. 4. The pulse shaping circuit includes a comparator that compares the detected voltage of the primary current with a reference voltage, and the logic circuit is an AND gate having three input terminals and is responsive to the pulse signal. The ignition signal detection device for an internal combustion engine according to claim 2, wherein the voltage signal is used as the third input signal.